Climate Change Chart of Kingston, Norfolk Island

Overview of climate changes

Temperature changes

Averaged across calendar months, monthly mean temperature showed a difference of +0.81 °C compared with the earlier reference period. This is an unweighted mean of monthly means, not a day-weighted annual average, and it describes the overall monthly-average difference rather than a change in every month. The largest monthly increase was in May, with a difference of +1.22 °C; this identifies the strongest increase, not the pattern for all other months. These values describe monthly mean temperatures, not daytime maximum temperatures.

Changes in rainfall

Mean daily rainfall averaged across calendar months had a difference of +0.09 mm/day in the more recent period. This unweighted average of monthly means does not imply that rainfall increased in every month, and the figures are daily means rather than monthly totals. The largest monthly increase was in February, at a difference of +1.45 mm/day, while the largest monthly decrease was in May, at a difference of -1.35 mm/day. Together, these contrasting monthly changes show why the small overall mean difference should not be read as a uniform month-by-month shift.

Changes in sunshine duration

Mean daily sunshine duration, averaged across calendar months, had a difference of -0.37 hours/day compared with the earlier reference period. This is an unweighted average of monthly means, so it summarizes the calendar-month averages rather than indicating the same change in each month. The largest monthly decrease occurred in December, with a difference of -0.59 hours/day. The sunshine figures are mean daily hours, not monthly totals; the monthly decrease and overall mean provide distinct views of the comparison.